Add support for "editor" content types for compare editor

team/bundles/org.eclipse.compare/.settings/.api_filters

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<component id="org.eclipse.compare" version="2">
+    <resource path="META-INF/MANIFEST.MF">
+        <filter comment="Changed contentMergeViewers extension point" id="926941240">
+            <message_arguments>
+                <message_argument value="3.11.0"/>
+                <message_argument value="3.10.0"/>
+            </message_arguments>
+        </filter>
+    </resource>
+</component>

team/bundles/org.eclipse.compare/META-INF/MANIFEST.MF

@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.compare; singleton:=true
-Bundle-Version: 3.10.100.qualifier
+Bundle-Version: 3.11.0.qualifier
 Bundle-Activator: org.eclipse.compare.internal.CompareUIPlugin
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin

team/bundles/org.eclipse.compare/compare/org/eclipse/compare/CompareViewerSwitchingPane.java

@@ -15,6 +15,7 @@
 
 import java.text.MessageFormat;
 
+import org.eclipse.compare.contentmergeviewer.ContentMergeViewer;
 import org.eclipse.compare.contentmergeviewer.IFlushable;
 import org.eclipse.compare.internal.CompareMessages;
 import org.eclipse.compare.internal.IFlushable2;
@@ -279,9 +280,15 @@ public void setInput(Object input) {
 		if (fViewer != null) {
 			Control c= fViewer.getControl();
 			if (c != null) {
-				Object data= c.getData(CompareUI.COMPARE_VIEWER_TITLE);
-				if (data instanceof String)
-					title= (String) data;
+				if (fViewer instanceof ContentMergeViewer cmv) {
+					title = cmv.getTitle();
+				}
+				if (title == null || title.isBlank()) {
+					Object data = c.getData(CompareUI.COMPARE_VIEWER_TITLE);
+					if (data instanceof String) {
+						title = (String) data;
+					}
+				}
 				if (hadFocus)
 					c.setFocus();
 			}

team/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/CompareUIPlugin.java

@@ -33,9 +33,12 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Optional;
 import java.util.ResourceBundle;
 import java.util.Set;
 import java.util.StringTokenizer;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.eclipse.compare.CompareConfiguration;
 import org.eclipse.compare.CompareEditorInput;
@@ -77,6 +80,7 @@
 import org.eclipse.swt.widgets.Composite;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Shell;
+import org.eclipse.ui.IEditorDescriptor;
 import org.eclipse.ui.IEditorInput;
 import org.eclipse.ui.IEditorPart;
 import org.eclipse.ui.IEditorRegistry;
@@ -192,6 +196,10 @@ List<T> searchAll(String extension) {
 				return fExtensionMap.get(normalizeCase(extension));
 			return null;
 		}
+
+		Collection<T> getAll() {
+			return fIdMap == null ? Collections.emptySet() : fIdMap.values();
+		}
 	}
 
 	/** Status code describing an internal error */
@@ -983,7 +991,7 @@ private Collection<Object> getContentTypes(Object in) {
 	}
 
 	public ViewerDescriptor[] findContentViewerDescriptor(Viewer oldViewer, Object in, CompareConfiguration cc) {
-		Set<ViewerDescriptor> result = new LinkedHashSet<>();
+		LinkedHashSet<ViewerDescriptor> result = new LinkedHashSet<>();
 		if (in instanceof IStreamContentAccessor) {
 			String type= ITypedElement.TEXT_TYPE;
 
@@ -1016,6 +1024,7 @@ public ViewerDescriptor[] findContentViewerDescriptor(Viewer oldViewer, Object i
 			return null;
 
 		ICompareInput input= (ICompareInput) in;
+		String name = input.getName();
 
 		IContentType ctype = getCommonType(input);
 		if (ctype != null) {
@@ -1054,6 +1063,9 @@ public ViewerDescriptor[] findContentViewerDescriptor(Viewer oldViewer, Object i
 				result.addAll(list);
 		}
 
+		Set<ViewerDescriptor> editorLinkedDescriptors = findEditorLinkedDescriptors(name, ctype, false);
+		result.addAll(editorLinkedDescriptors);
+
 		// fallback
 		String leftType= guessType(input.getLeft());
 		String rightType= guessType(input.getRight());
@@ -1069,14 +1081,79 @@ public ViewerDescriptor[] findContentViewerDescriptor(Viewer oldViewer, Object i
 					result.addAll(list);
 			}
 			List<ViewerDescriptor> list = fContentMergeViewers.searchAll(ITypedElement.TEXT_TYPE);
-			if (list != null)
+			if (list != null) {
 				result.addAll(list);
-
-			return result.toArray(new ViewerDescriptor[0]);
+			}
 		}
+
+		ensureTextIsLast(result);
 		return result.isEmpty() ? null : result.toArray(new ViewerDescriptor[0]);
 	}
 
+	/**
+	 * Modifies given set to move "fallback" text descriptor to be the last one.
+	 * This is needed because we want more specific descriptors used first by default.
+	 */
+	private static void ensureTextIsLast(LinkedHashSet<ViewerDescriptor> result) {
+		if (result.size() > 1) {
+			ViewerDescriptor first = result.iterator().next();
+			if (TextMergeViewerCreator.class.getName().equals(first.getViewerClass())) {
+				result.remove(first);
+				result.add(first);
+			}
+		}
+	}
+
+	/**
+	 * @param fileName      possible file name for content in compare editor, may be
+	 *                      null
+	 * @param contentType   possible content type for content in compare editor, may
+	 *                      be null
+	 * @param firstIsEnough stop searching once first match is found
+	 * @return set of descriptors which could be found for given content type via
+	 *         "linked" editor
+	 */
+	Set<ViewerDescriptor> findEditorLinkedDescriptors(String fileName, IContentType contentType,
+			boolean firstIsEnough) {
+		if (fileName == null) {
+			if (contentType == null) {
+				contentType = fgContentTypeManager.findContentTypeFor(fileName);
+			} else {
+				return Collections.emptySet();
+			}
+		}
+
+		LinkedHashSet<ViewerDescriptor> viewers = fContentMergeViewers.getAll().stream()
+				.filter(vd -> vd.getLinkedEditorId() != null).collect(Collectors.toCollection(LinkedHashSet::new));
+		if (viewers.isEmpty()) {
+			return Collections.emptySet();
+		}
+
+		IEditorRegistry editorReg = PlatformUI.getWorkbench().getEditorRegistry();
+		LinkedHashSet<ViewerDescriptor> result = new LinkedHashSet<>();
+		IEditorDescriptor[] editors = editorReg.getEditors(fileName, contentType);
+		for (IEditorDescriptor ed : editors) {
+			addLinkedEditorContentTypes(viewers, firstIsEnough, ed.getId(), result);
+			if (firstIsEnough && !result.isEmpty()) {
+				return result;
+			}
+		}
+		return result;
+	}
+
+	private void addLinkedEditorContentTypes(LinkedHashSet<ViewerDescriptor> viewers, boolean firstIsEnough,
+			String editorId, Set<ViewerDescriptor> result) {
+		Stream<ViewerDescriptor> stream = viewers.stream().filter(vd -> editorId.equals(vd.getLinkedEditorId()));
+		if (firstIsEnough) {
+			Optional<ViewerDescriptor> first = stream.findFirst();
+			if (first.isPresent()) {
+				result.add(first.get());
+			}
+		} else {
+			stream.collect(Collectors.toCollection(() -> result));
+		}
+	}
+
 	/**
 	 * Returns a content compare viewer based on an old viewer and an input object.
 	 * If the old viewer is suitable for showing the input the old viewer
@@ -1483,6 +1560,11 @@ String findContentTypeNameOrType(ICompareInput input, ViewerDescriptor vd, Compa
 					return type;
 		}
 
+		Set<ViewerDescriptor> editorLinkedDescriptors = findEditorLinkedDescriptors(input.getName(), ctype, true);
+		if (!editorLinkedDescriptors.isEmpty()) {
+			return type;
+		}
+
 		// fallback
 		String leftType= guessType(input.getLeft());
 		String rightType= guessType(input.getRight());

team/bundles/org.eclipse.compare/compare/org/eclipse/compare/internal/ViewerDescriptor.java

@@ -27,6 +27,7 @@
 public class ViewerDescriptor implements IViewerDescriptor {
 	private final static String CLASS_ATTRIBUTE= "class"; //$NON-NLS-1$
 	private final static String EXTENSIONS_ATTRIBUTE= "extensions"; //$NON-NLS-1$
+	private final static String LINKED_EDITOR_ATTRIBUTE = "linkedEditor"; //$NON-NLS-1$
 	private final static String LABEL_ATTRIBUTE = "label"; //$NON-NLS-1$
 
 	private final IConfigurationElement fConfiguration;
@@ -79,4 +80,42 @@ public String getExtension() {
 	String getLabel() {
 		return fConfiguration.getAttribute(LABEL_ATTRIBUTE);
 	}
+
+	String getLinkedEditorId() {
+		return fConfiguration.getAttribute(LINKED_EDITOR_ATTRIBUTE);
+	}
+
+	String getViewerClass() {
+		return fConfiguration.getAttribute(CLASS_ATTRIBUTE);
+	}
+
+	@SuppressWarnings("nls")
+	@Override
+	public String toString() {
+		StringBuilder sb = new StringBuilder();
+		sb.append("ViewerDescriptor [");
+		if (fViewerClass != null) {
+			sb.append("viewerClass=");
+			sb.append(fViewerClass);
+			sb.append(", ");
+		}
+		if (fViewerCreator != null) {
+			sb.append("viewerCreator=");
+			sb.append(fViewerCreator);
+			sb.append(", ");
+		}
+		String viewerClass = getViewerClass();
+		if (viewerClass != null) {
+			sb.append("viewerClass=");
+			sb.append(viewerClass);
+			sb.append(", ");
+		}
+		if (fConfiguration != null) {
+			sb.append("configuration=");
+			sb.append(fConfiguration);
+		}
+		sb.append("]");
+		return sb.toString();
+	}
+
 }

team/bundles/org.eclipse.compare/schema/contentMergeViewers.exsd

@@ -90,6 +90,17 @@ content merge viewer and implements <samp>org.eclipse.compare.IViewerCreat
                </appInfo>
             </annotation>
          </attribute>
+         <attribute name="linkedEditor" type="string">
+            <annotation>
+               <documentation>
+                  Since 3.11. Editor id to consider while searching for a viewer matching a content type. 
+If the specified &quot;linked&quot; editor has content type associations, they will be also considered as possible bindings for this viewer. This is useful in cases where viewer supports same content types as &quot;linked&quot; editor (like in generic editor).
+               </documentation>
+               <appInfo>
+                  <meta.attribute kind="identifier" basedOn="org.eclipse.ui.editors/editor/@id"/>
+               </appInfo>
+            </annotation>
+         </attribute>
       </complexType>
    </element>
 
@@ -123,6 +134,7 @@ content merge viewer and implements &lt;samp&gt;org.eclipse.compare.IViewerCreat
       </complexType>
    </element>
 
+
    <annotation>
       <appInfo>
          <meta.section type="examples"/>
@@ -154,7 +166,6 @@ for text files (extension &quot;txt&quot;):
       </documentation>
    </annotation>
 
-
    <annotation>
       <appInfo>
          <meta.section type="implementation"/>